. >> reporter: vice president joe biden leads the u.s. delegation. today he met with the president and prime minister of italy while pope francis held his first audience with the head of state. argentinean president said i've never been kissed by a pope before as she gave francis a gift. traditional argentine cups used to drink the country's national beverage. they were at odds over social issues when he was the archbishop of buenos aires. hundreds of thousands expected to pack the gnawicity for the inaugural mass. >> reports are that there's an excitement about this. >> reporter: excitement building since the election as a result of his personal style. francis enjoys reaching out to faithful and vatican anticipates that it will be the case on tuesday as well. >> clearly a solemn day. with everything the pope has done so far, we see he has a people's touch at the same time. i expect we'll see that tomorrow as well. >> reporter: a touch that has come to define the early days of his papacy. the vatican announced today that pope francis will tour st. pe